Medical Gas Flashcards
Name some regulatory agencies that have written guidelines for medical gas systems.
- department of transportation (DOT)
- national fire prevention association (NFPA)
- compressed gas association (CGA)
- american national standards institute (ANSI)
- US pharmacopeia
- interstate commerce commission (ICC)
What is medical compressed gas as defined by the Interstate Commerce Commission (ICC)?
Any material or mixture having in the container either an absolute pressure exceeding 40 lb/psi at 130 degrees Fahrenheit or any liquid flammable material having a vapor pressure exceeding 40 lb/psi at 100 degrees Fahrenheit
What does the department of transportation do?
Agency regulates design, construction, testing, marketing, labeling, filling, storage, handling, maintenance, and transportation of compressed gas cylinders
What material makes up the body of the compressed gas cylinder?
The body is usually a steel body with a flat bottom, tapered neck, and about 3/8 inch thick
*aluminum alloy gas containers need to be used during MRIs
Name the different parts of the gas cylinder.
- port: point of exit for the gas
- valve: made of bronze or brass; attached to the neck of the tank
- pressure relief valve: vents the cylinder under high pressure
- conical depression: fits the retaining screw of the yoke
- stem: moves up to open and down to close
What are the pin positions for oxygen?
2 and 5
What are the pin positions for air?
1 and 5
What are the pin positions for nitrous oxide?
3 and 5
What are the pin positions for carbon dioxide?
2 and 6
Describe the pin index safety system (PISS).
- Safety system used for cylinder gas
- helps prevent gas mix ups
- there are two holes on each cylinder valve that are positioned to correspond with two pins on the yokes for each gas
- each gas has unique pin positions that will only fit their specific cylinder valve
Describe the diameter index safety system (DISS).
- safety mechanism for pipeline gas supply
- each pipeline outlet has a different diameter for each gas and its respective hoses
What are the US and international cylinder colors for oxygen?
US-green
International-white
What are the cylinder colors for nitrous oxide?
Blue
What are the cylinder colors for air?
Yellow
What are the cylinder colors for helium?
Black
What are the cylinder colors for carbon dioxide?
Grey
What is an E tank?
Most common tank seen and fits anesthesia machine
What is the weight of an E tank?
14 lbs
What are the E tank capacities for air?
Max pressure 1900 psig
Max volume 625 L
What are the E tank capacities for oxygen?
Max pressure 1900 psig
Max volume 660 L
What are the E tank capacities of nitrous oxide?
Max pressure 745 psig
Max volume 1590 L
*pressure may still read 745 psig down to 250 L so you can’t relay on gauge pressure reading to determine amount of N2O remaining
What are some special E tank consideration for N2O?
- nitrous oxide is stored as a liquid at room temperature since its critical temperature is 36.5 degrees C
- when N2O is removed at >4 L/min, frost lines will form on the outside of tank
How do you measure E tank contents of N2O?
- must use the weight of the tank rather than gauge pressure
- subtract the weight of the empty tank (14 lb) from the total weight
- convert the remaining weight from lbs to kg (divide by 2.2)
- convert kg to g (multiply by 1,000)
- multiply g by 0.55 to get Liters of N2O
- 1 gram of N2O equals 0.55 L of N2O at 20 degree C*
How do you calculate the amount of O2 remaining in the E tank?
- look at the current gauge pressure and determine its percentage of oxygen’s full gauge pressure (1900 psig)
- find that same percentage of oxygen’s full volume (660 L)
- determine the remaining time by dividing the remaining Liters by the flow time (L/min) to get the remaining minutes
Describe gas container testing.
- tested every five years (unless starred)
- service pressure is tested to a minimum of 1.6 times the service pressure
- test date (month and year) is required to be permanently stamped on the cylinder
Describe container labeling.
- required on ALL cylinders
- usually on the shoulder of the cylinder
- indicates contained gas and triangles indicate hazard class of gas
Describe container markings.
permanently stamped on the shoulder of the cylinder
- service pressure- max pressure the cylinder can be filled
- manufacturer
- serial number
- plus sign-indicates the cylinder can be charged up to 10% in excess of service pressure
- star-indicates testing is only required every 10 years
What hazard class does a yellow triangle indicate?
Oxidizer gas
What hazard class does a red triangle indicate?
Flammable gas
What hazard class does a green triangle indicate?
Non-flammable gas
Describe safe cylinder storage.
- cool, clean, dry area
- nowhere near flame, spark, or heat sources
- out of direct sunlight
- store upright in rack
- if no rack, lie on side (NO FREESTANDING)
Describe pipeline gas.
- Hose colors are usually the same as the tank
- wall terminal uses quick couplers
- safety- DISS
- pressures are 50-55 psig from terminal
What are some concerns with pipeline gas?
- hose disconnect from hanging ceiling connection of from wall
- particulate material contaminating the line
- hoses across the floor can be occluded from heavy equipment
Name six hazards of medical gas.
- fires
- incorrect contents
- damaged or inoperable valve
- explosion
- contaminated contents
- high pressure release
What are 3 sources of medical gas in central supply of facilities?
- bulk supply system (usually liquid)
- two tank banks (small facilities)
- tank banks to back up bulk supply
